The presence of vapors, and their concentration in air, is monitored in many fields of endeavor. Various methods for detecting vapors (e.g., volatile organic compounds (VOCs)) have been developed including, for example, photoionization, gas chromatography, gravimetric techniques, spectroscopic techniques (e.g., mass spectrometry, infrared spectroscopy, or fluorescence spectroscopy), and absorptive sensing techniques.
In capacitance sensors, the capacitance of two conductive electrodes (typically parallel or interdigitated), varies as the dielectric constant of material between the two electrodes changes due to the presence of an environmental analyte vapor.
Conventional capacitance sensors are typically complex mechanical devices in which a sensor is disposed within a rigid housing. However, such devices can be expensive to make, and may not be well-suited for applications in which they need to be mounted to an uneven and/or curved surface.